The present invention relates to an air filter system and to a method for maintaining an air filter having an axial flow air filter element.
Axial flow filter elements are used in many areas in which a gas or a liquid is to be filtered. These elements are inserted in many types of housings for this purpose and must be replaced or cleaned as directed after reaching a specific load or after predefined maintenance intervals.
U.S. Pat. No. 6,350,291 (=EP 1,159,052) discloses a filter element having a frame construction, which is bonded annularly to the jacket surface of the filter element in the area of one of the axial end faces and has an extension which projects axially beyond the axial end face. In turn, a sealing element is arranged on the extension, which is positioned at least partially around the external peripheral surface of the extension. In this way, a tight connection to the interior of an air filter housing is ensured.
It is disadvantageous for this purpose that the interior of the frame construction for attachment to the jacket surface of the filter element may not have any deviation in diameter from the external diameter of the jacket surface, since otherwise there may be a connection between the unfiltered and filtered sides of the filter element. For this purpose, very tight manufacturing tolerances must be maintained both for the frame construction and for the filter element jacket, which are associated with increased costs.